In some rare cases queries with UNION ALL
using a derived table specified by
a grouping select with a subquery in WHERE and
impossible HAVING detected after constant row
substitution could hang.
The cause was not a proper return from the
function subselect_single_select_engine::exec()
in the case when the subquery was not optimized
beforehand and the optimization performed
in this function requested for a change of the
subquery engine. This was fixed.
Also a change was applied that avoided execution
of a subquery if impossible having was detected
for the main query at the optimization stage.
Introducing a new class Type_holder (used internally in sql_union.cc),
to reuse exactly the same data type attribute aggregation Type_handler API
for hybrid functions and UNION.
This fixes a number of bugs in UNION:
- MDEV-9495 Wrong field type for a UNION of a signed and an unsigned INT expression
- MDEV-9497 UNION and COALESCE produce different field types for DECIMAL+INT
- MDEV-12594 UNION between fixed length double columns does not always preserve scale
- MDEV-12595 UNION converts INT to BIGINT
- MDEV-12599 UNION is not symmetric when mixing INT and CHAR
Details:
- sql_union.cc: Reusing attribute aggregation for UNION.
Adding new methods:
* st_select_lex_unit::join_union_type_handlers()
* st_select_lex_unit::join_union_type_attributes()
* st_select_lex_unit::join_union_item_types()
Removing the old join_types()-based code.
- Changing Type_handler::Item_hybrid_func_fix_attributes()
to accept "name", Type_handler_hybrid_field_type, Type_all_attributes
as three separate parameters instead of a single Item_hybrid_func parameter,
to make it possible to pass both Item_hybrid_func and Type_holder.
- Moving the former special GEOMETRY and ENUM/SET attribute aggregation code
from Item_type_holder::join_types() to
* Type_handler_typelib::Item_hybrid_func_fix_attributes().
* Type_handler_geometry::Item_hybrid_func_fix_attrubutes().
This makes GEOMETRY/ENUM/SET symmetric with all other data types
(from the UNION point of view).
Removing Item_type_holder::join_types() and Item_type_holder::get_full_info().
- Adding new methods into Type_all_attributes:
* Type_all_attributes::set_geometry_type() and
Item_hybrid_func::set_geometry_type().
* Adding Type_all_attributes::get_typelib().
* Adding Type_all_attributes::set_typelib().
- Adding Type_handler_typelib as a common parent for
Type_handler_enum and Type_handler_set, to avoid code duplication: they have
already had two common methods, and we're adding one more shared method.
- Adding Type_all_attributes::set_maybe_null(), as some type handlers
may want to set maybe_null (e.g. Type_handler_geometry) during data type
attribute aggregation.
- Changing Type_geometry_attributes() to accept Type_handler
and Type_all_attributes as two separate parameters, instead
of a single Item parameter, to make it possible to pass Type_holder.
- Adding Item_args::add_argument().
- Moving Item_args::alloc_arguments() from "protected" to "public".
- Moving Item_type_holder::Item_type_holder() from item.cc to item.h, as
now it's very simple.
Btw, this constructor should probably be eventually removed.
It's now used only in sql_show.cc, which could be modified to use
Item_return_decimal (for symmetry with Item_return_xxx created for all
other data types). Or, another option: remove all Item_return_xxx and
use Item_type_holder for all data types instead.
- storage/tokudb/mysql-test/tokudb/r/type_float.result
Recording new results (MDEV-12594).
- mysql-test/r/cte_recursive.result
Recording new results (MDEV-9497)
- mysql-test/r/subselect*.result
Recording new results (MDEV-12595)
- mysql-test/r/metadata.result
Recording new results (MDEV-9495)
- mysql-test/r/temp_table.result
Recording new results (MDEV-12594)
- mysql-test/r/type_float.result
Recording new results (MDEV-12594)
- Adding Type_handler::make_table_field() and moving pieces of the code
from Item::tmp_table_field_from_field_type() to virtual implementations
for various type handlers.
- Adding a new Type_all_attributes, to access to Item's extended
attributes, such as decimal_precision() and geometry_type().
- Adding a new class Record_addr, to pass record related information
to Type_handler methods (ptr, null_ptr and null_bit) as a single structure.
Note, later it will possibly be extended for BIT-alike field purposes,
by adding new members (bit_ptr_arg, bit_ofs_arg).
- Moving the code from Field_new_decimal::create_from_item()
to Type_handler_newdecimal::make_table_field().
- Removing Field_new_decimal() and Field_geom() helper constructor
variants that were used for temporary field creation.
- Adding Item_field::type_handler(), Field::type_handler() and
Field_blob::type_handler() to return correct type handlers for
blob variants, according to Field_blob::packlength.
- Adding Type_handler_blob_common, as a common parent for
Type_handler_tiny_blob, Type_handler_blob, Type_handler_medium_blob
and Type_handler_long_blob.
- Implementing Type_handler_blob_common::Item_hybrid_func_fix_attributes().
It's needed for cases when TEXT variants of different character sets are mixed
in LEAST, GREATEST, CASE and its abreviations (IF, IFNULL, COALESCE), e.g.:
CREATE TABLE t1 (
a TINYTEXT CHARACTER SET latin1,
b TINYTEXT CHARACTER SET utf8
);
CREATE TABLE t2 AS SELECT COALESCE(a,b) FROM t1;
Type handler aggregation returns TINYTEXT as a common data type
for the two columns. But as conversion from latin1 to utf8
happens for "a", the maximum possible length of "a" grows from 255 to 255*3.
Type_handler_blob_common::Item_hybrid_func_fix_attributes() makes sure
to update the blob type handler according to max_length.
- Adding Type_handler::blob_type_handler(uint max_octet_length).
- Adding a few m_type_aggregator_for_result.add() pairs, because
now Item_xxx::type_handler() can return pointers to type_handler_tiny_blob,
type_handler_blob, type_handler_medium_blob, type_handler_long_blob.
Before the patch only type_handler_blob was possible result of type_handler().
- Making type_handler_tiny_blob, type_handler_blob, type_handler_medium_blob,
type_handler_long_blob public.
- Removing the condition in Item_sum_avg::create_tmp_field()
checking Item_sum_avg::result_type() against DECIMAL_RESULT.
Now both REAL_RESULT and DECIMAL_RESULT are symmetrically handled
by tmp_table_field_from_field_type().
- Removing Item_geometry_func::create_field_for_create_select(),
as the inherited version perfectly works.
- Fixing Item_func_as_wkb::field_type() to return MYSQL_TYPE_LONG_BLOB
rather than MYSQL_TYPE_BLOB. It's needed to make sure that
tmp_table_field_from_field_type() creates a LONGBLOB field for AsWKB().
- Fixing Item_func_as_wkt::fix_length_and_dec() to set max_length to
UINT32_MAX rather than MAX_BLOB_WIDTH, to make sure that
tmp_table_field_from_field_type() creates a LONGTEXT field for AsWKT().
- Removing Item_func_set_user_var::create_field_for_create_select(),
as the inherited version works fine.
- Adding Item_func_get_user_var::create_field_for_create_select() to
make sure that "CREATE TABLE t1 AS SELECT @string_user variable"
always creates a field of LONGTEXT/LONGBLOB type.
- Item_func_ifnull::create_field_for_create_select()
behavior has changed. Before the patch it passed set_blob_packflag=false,
which meant to create LONGBLOB for all blob variants.
Now it takes into account max_length, which gives better column
data types for:
CREATE TABLE t2 AS SELECT IFNULL(blob_column1, blob_column2) FROM t1;
- Fixing Item_func_nullif::fix_length_and_dec() to use
set_handler(args[2]->type_handler()) instead of
set_handler_by_field_type(args[2]->field_type()).
This is needed to distinguish between BLOB variants.
- Implementing Item_blob::type_handler(), to make sure to create
proper BLOB field variant, according to max_length, for queries like:
CREATE TABLE t1 AS
SELECT some_blob_field FROM INFORMATION_SCHEMA.SOME_TABLE;
- Fixing Item_field::real_type_handler() to make sure that
the code aggregating fields for UNION gets a proper BLOB
variant type handler from fields.
- Adding a special code into Item_type_holder::make_field_by_type(),
to make sure that after aggregating field types it also properly
takes into account max_length when mixing TEXT variants of different
character sets and chooses a proper TEXT variant:
CREATE TABLE t1 (
a TINYTEXT CHARACTER SET latin1,
b TINYTEXT CHARACTER SET utf8
);
CREATE TABLE t2 AS SELECT a FROM t1 UNION SELECT b FROM t1;
- Adding tests, for better coverage of IFNULL, NULLIF, UNION.
- The fact that tmp_table_field_from_field_type() now takes
into account BLOB variants (instead of always creating LONGBLOB),
tests results for WEIGHT_STRING() and NULLIF() and UNION
have become more precise.
Print default values for BLOB's.
This is a part commit for automatic changes to make the real commit smaller.
All changes here are related to that we now print DEFAULT NULL for blob and
text fields, like we do for all other fields.
The method subselect_union_engine::no_rows() must take
into account the fact that now unit->fake_select_lex is
NULL for for select_union_direct objects.
~40% bugfixed(*) applied
~40$ bugfixed reverted (incorrect or we're not buggy)
~20% bugfixed applied, despite us being not buggy
(*) only changes in the server code, e.g. not cmakefiles
Bug #18167356: EXPLAIN W/ EXISTS(SELECT* UNION SELECT*)
WHERE ONE OF SELECT* IS DISTINCT FAILS.
the bugfix itself was not merged - MariaDB doesn't have this bug.
ISSUE:
------
For UNION of selects, rows examined by the query will be sum
of rows examined by individual select operations and rows
examined for union operation. The value of session level
global counter that is used to count the rows examined by a
select statement should be accumulated and reset before it
is used for next select statement. But we have missed to
reset the same. Because of this examined row count of a
select query is accounted more than once.
SOLUTION:
---------
In union reset the session level global counter used to
accumulate count of examined rows after its value is saved.
mysql-test/r/union.result:
Expected output of testcase added.
mysql-test/t/union.test:
Test to verify examined row count of Union operations.
sql/sql_union.cc:
Reset the value of thd->examined_row_count after
accumulating the value.
When marking used columns the function find_field_in_table_ref() erroneously
called the walk method for the real item behind a view/derived table field
with the second parameter set to TRUE.
This erroneous code was introduced in 2006.
The bug prevented acceptance of UNION queries whose non-first select
clauses contained join expressions with degenerated single-table nests
as valid queries.
The bug was introduced into mysql-5.5 code line by the patch for
bug 33204.
* rename all debugging related command-line options
and variables to start from "debug-", and made them all
OFF by default.
* replace "MySQL" with "MariaDB" in error messages
* "Cast ... converted ... integer to it's ... complement"
is now a note, not a warning
* @@query_cache_strip_comments now has a session scope,
not global.
sql/sql_insert.cc:
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
******
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
sql/sql_table.cc:
small cleanup
******
small cleanup
We must allocate a larger ref_pointer_array. We failed to account for extra
items allocated here:
#0 find_order_in_list
uint el= all_fields.elements;
all_fields.push_front(order_item); /* Add new field to field list. */
ref_pointer_array[el]= order_item;
order->item= ref_pointer_array + el;
#1 setup_order
#2 setup_without_group
#3 JOIN::prepare
mysql-test/r/order_by.result:
New test case.
mysql-test/r/union.result:
New test case.
mysql-test/t/order_by.test:
New test case.
mysql-test/t/union.test:
New test case.
sql/sql_lex.cc:
find_order_in_list() may need some extra space, so multiply og_num by two.
sql/sql_union.cc:
For UNION, the 'n_sum_items' are accumulated in the "global_parameters" select_lex.
This number must be propagated to setup_ref_array()
When preparing a 'fake_select_lex' we need to use global_parameters->order_list
rather than fake_select_lex->order_list (see comments inside st_select_lex_unit::cleanup)
A lot of small fixes and new test cases.
client/mysqlbinlog.cc:
Cast removed
client/mysqltest.cc:
Added missing DBUG_RETURN
include/my_pthread.h:
set_timespec_time_nsec() now only takes one argument
mysql-test/t/date_formats.test:
Remove --disable_ps_protocl as now also ps supports microseconds
mysys/my_uuid.c:
Changed to use my_interval_timer() instead of my_getsystime()
mysys/waiting_threads.c:
Changed to use my_hrtime()
sql/field.h:
Added bool special_const_compare() for fields that may convert values before compare (like year)
sql/field_conv.cc:
Added test to get optimal copying of identical temporal values.
sql/item.cc:
Return that item_int is equal if it's positive, even if unsigned flag is different.
Fixed Item_cache_str::save_in_field() to have identical null check as other similar functions
Added proper NULL check to Item_cache_int::save_in_field()
sql/item_cmpfunc.cc:
Don't call convert_constant_item() if there is nothing that is worth converting.
Simplified test when years should be converted
sql/item_sum.cc:
Mark cache values in Item_sum_hybrid as not constants to ensure they are not replaced by other cache values in compare_datetime()
sql/item_timefunc.cc:
Changed sec_to_time() to take a my_decimal argument to ensure we don't loose any sub seconds.
Added Item_temporal_func::get_time() (This simplifies some things)
sql/mysql_priv.h:
Added Lazy_string_decimal()
sql/mysqld.cc:
Added my_decimal constants max_seconds_for_time_type, time_second_part_factor
sql/table.cc:
Changed expr_arena to be of type CONVENTIONAL_EXECUTION to ensure that we don't loose any items that are created by fix_fields()
sql/tztime.cc:
TIME_to_gmt_sec() now sets *in_dst_time_gap in case of errors
This is needed to be able to detect if timestamp is 0
storage/maria/lockman.c:
Changed from my_getsystime() to set_timespec_time_nsec()
storage/maria/ma_loghandler.c:
Changed from my_getsystime() to my_hrtime()
storage/maria/ma_recovery.c:
Changed from my_getsystime() to mmicrosecond_interval_timer()
storage/maria/unittest/trnman-t.c:
Changed from my_getsystime() to mmicrosecond_interval_timer()
storage/xtradb/handler/ha_innodb.cc:
Added support for new time,datetime and timestamp
unittest/mysys/thr_template.c:
my_getsystime() -> my_interval_timer()
unittest/mysys/waiting_threads-t.c:
my_getsystime() -> my_interval_timer()
